Rosy Reds are, IMHO, highly underrated fish. They breed readily; spawn and guard their nests much like cichlids; they'll live decently well in heated tanks with tropicals, but also survive handily under thick ice in a pond and actually live longer with a yearly cool-off period; and they display well with their bright colouration. And, as a bonus, they are one of the stupidest fish we keep, so catching them out of a pond or container to relocate them is extremely simple.
A large school of Rosies in a pond or stock tank, swarming to the surface when food is offering, is a beautiful and relaxing sight.
Lots of online sources state that they have very short lifespans, but I have had many that lived over three years and a few that survived over four.